Duncan wrote:I don't believe it is more dense because of the pressure, however if it's colder or warmer it will change the density. Water is most dense at around 4 degrees if I remember right, and gets less dense the warmer or colder you go from there.
I think you're right. It's at 4 degrees that ice crystals start to form in water (there is a 'Maximum Ice Formation Zone' - ask any butcher) and, as ice has more volume than water (it floats after all) it expands. Something that puzzles me though. Usually, tepmerature increases with pressure. So if the pressure down there is 16000psi, how come the temperature is approaching Absolute Zero? Isn't there a Physics teacher on here?
Yes pressure does normally result in a temperature increase but only on the scale of magnitudes larger than what the oceans can provide
With regards to the oceans, it's simply colder down there because of the lack of sunlight that reaches those parts. The only warming is from thermal vents. Incidentally - as the pressure increases the water cannot form ice crystals as readily so it doesn't actually freeze down there despite being rather chilly. And for the followers of absolute zero, we have this from Wikipedia:-
Absolute zero is the theoretical temperature at which entropy reaches its minimum value. The laws of thermodynamics state that absolute zero cannot be reached using only thermodynamic means. A system at absolute zero still possesses quantum mechanical zero-point energy, the energy of its ground state. The kinetic energy of the ground state cannot be removed. However, in the classical interpretation it is zero and the thermal energy of matter vanishes.
The zero point of any thermodynamic temperature scale, such as Kelvin or Rankine, is set at absolute zero. By international agreement, absolute zero is defined as 0K on the Kelvin scale and as Ã¢Ë†â€™273.15Ã‚Â° on the Celsius scale. This equates to Ã¢Ë†â€™459.67Ã‚Â° on the Fahrenheit scale and 0 R on the Rankine scale. Scientists have achieved temperatures very close to absolute zero, where matter exhibits quantum effects such as superconductivity and superfluidity.